Mechanical hammer



June 12, 1928. 1,672,885

R. GOLDSCHMIDT MECHAN I CAL HAMMER Filed June 17, 1925 PYcssur-e of 5brmg INVENTOR 3 I Rude/f Go/dsr rm/dfi 4 ITORNEV Patented June 12, 1928.

, UNITED STATES BUDOLF GOLDSCHMIDT, F CHABLOTTEI IBUBG, GEBIANY.

' uacnnmcn. maxim Application filed June 11, 1925. Serial Io. amas Myinvention has special relation to mechanical hammers and moreparticularly to those of the type set forth in my United States LettersPatent No. 1,386,329, issued 6 August 2, 1921, wherein is disclosed avery eflicient way of converting rotary motion into hammer action. Themethod comprises attaching to the hammer or tup one or more flyweightsthat are driven from a motor, and at the same time exercising aunidirectional force on the hammer preferably bythe pressure of aspring. The rotating flyweights develop centrifugal force impartingreciprocatory motion upon the tup, the unidirec- 1 tional force causinthe hammer to deliver a stroke in a certain direction. I have discoveredthat certain definite relations exist between the centrifugal force witha variable direction and the unidirectional force of the spring. Theforegoing relations are thesubject of this patent application.

In order that the invention may be more readily understood, reference ismade the attached drawings, wherein:

Figure 1 shows a vertical section through a simple form of hammer;

Figs. 2, 3, 4 and 5 are diagrammatic views and curves relating tothedesign and working of the hammer.

The design of hammer shown as an example in Figs. 1 and 2 is not themost practical type, but is a simple form, and appears to be best forexplaining the conditions being dealt with in this application.

In Figs. 1 and 2, 1 is the hammer or the tup which moves up and down anddelivers the stroke upon the tool or anvil 10. 3 is a shaft whichrotates in the bearings 4 in the tup and which is driven by the motor 9through the medium of two clutches 6 and 7 and the flexible shaft 8. Aneccentric fly weight 5 is fixed on the shaft 3. The describedarrangement of drive has been chosen to allow maintenance of therotation during 4 the reciprocatory movement of the tup 1, The tup isenclosed in the casing 2. A spring 11 is inserted between the upperport-ion of the casin and the tup.

Throu h the rotation of the flyweight 5 a centri gal force C isexercised upon the tup 1, the direction of C varying according totheposition of the flywei ht 5. However, on y the components of in thedirection of the movement of the tup 1 is of import-ance at the presenttime. In this construction of the hammer a component at right angles tothe movement of the tup would tend to cause a lateral shaking of thehammer and the casing. The casing may be fixed to a foundation or be soheav that the vibrations become negligible, or t e lateral motion may becompensated for. As descr bed in previous patents, particularly my UmtedStates Letters Patent No. 1,386,329, issued August. 2, 1921, theseundesired forces can be compensated for.

The spring 11 exercises a unidirectional force P upon the tup in thedirection of its stroke. It is important that the spring exercise thisunidirectional force in every stage of the reciprocatory motion of thetup and in whatever position the hammer may be operating. That is to saythe tool and ham mer ma be operated in an upward position, at wh1c 1time the mass of the tup and the act on of gravity would be actingagainst the spring. If a sufficient blow is to be maintained in thisposition, the spring should have an initial tension or pressure 1 atleast equal to the weight of the tup 1 including the fiyweight 5.Accordingly, the spring will exercise a force upon the tap at all times,even at the moment of impact with the tool 10. Therefore, it will beunderstood that P is the average pressure for the time of one workingcycle, i. e., from one time of impact to the next time of impact.

When the tup 1 is moving upwardly under the action of the flyweights,the spring 11 is compressed, and its pressure increased directlyproportional to the amount of the lift, as will be apparent from thediagram in Figure 3.

The ratio between the centrifugal force C of the flyweight 5 and theaverage pressure P of the spring 11 may be determined from the followingformula derived with respect to the tri onometric functions of theangles between t e center line oftthe fiyweight and the line of tupmotion at moments of im- Wherein 0 may be designated as the speed of thetup at the moment of the impact; at the angle between the center line ofthe flyweight at the moment of the impact (Figure l) and the linedesignating the to motion; M the total reciprocatory mass the tup; and wthe angular velocity of the flyweight. B is the angle between the linedesignating the tup motion and the center line of the flyweight at themoment the tup is lifted. From a study of this formula it will be seenthat the highest speed of 'u will be obtained if the two angles, av andB are equal. i. e., if the new cycle begins immediately after one iscompleted. The parts may be so proportioned by having the centrifugalforce C equal to 'n' times the average pressure of the spring P.

\Vith this ratio of forces the tup will deliver one effective blow orstroke for each revolution of the flyweight. As the ratio of P times Cbecomes smaller. the stroke will become weaker and at 1:1, 5.1r ispractically zero.

It has been discovered that if the pressure of the spring relative tothe centrifugal force is still more reduced, an effective stroke isagain delivered at the ratio PXC 1X21 but under these conditions onlyone effective stroke or blow is delivered for each two revolutions ofthe fiyweight. Similarly, one blow may be obtained for each threerevolutions of the flyweight if the ratio of the spring pressure to thecentrifugal force is arranged as PEG- 1:31: etc.

Figure 5 sets forth a curve of working conditions, the abscissae beingthe ratio C x P and the ordinate is the speed '0 of the tup whencompleting a blow. It will be noted that these curves have distinctpeaks for a spring and weight in coaction similar to the well knownresonance curves and therefore, a certain tolerance in the ratio C x Pis permissible. It has been discovered that for most practical purposesthis tolerance may be I claim: v

1. In a mechanical hammer, the combina tion with a casing, a tup withinthe casing having a flyweight journaled thereon and means for rotatingsaid flyweight, of a. spring inserted between the casing and the end ofsaid tup, and concentrically disposed about said fiyweight, said springexercising an initial pressure corresponding to a force greater than theweight of the tup. I

2. In a mechanical hammer. the combination with a casing, a tap withinsaid casing, means for reciprocating said tup, and a spring forexercising pressure upon the top of said tup, said spring having aninitial compression pressure corresponding to a force greater than theweight of the tup and exercising a mean pressure during a cycle ofoperation with a tolerance of 3. In a mechanical hammer the combinationwith a casing, a reciprocatory tup within said casing for actuating atool exteriorof said casing, a coil spring member disposed between theinner end of said tup and said casing, a flyweight journaled on the in-'ner end of said tup and substantially en- RUDOLF GOLDSCHMID'T.

